Upstate New York's Catskill Mountain Range is a bucolic place near and dear to my heart. It's where storybook character Rip Van Winkle enjoyed his legendary slumber, and its scenery hasn't changed much since he was born of Washington Irving's fertile imagination. Yet, like Van Winkle, if I'd fallen asleep for 20 years when first arriving in that verdant heaven, I, too, would have noticed some profound changes upon awakening.

About two decades ago, many rural Catskill teens — sons of farmers and hunters and fishermen — suddenly started donning baggy pants and reflecting "gangsta'" counter-culture despite living nowhere near any large urban center. The following generation of teens experienced today's recent cultural evolution and often sport multiple tattoos and body piercings despite living nowhere near NYC's grungy East Village. Yet I'm wrong in a sense: those places were actually very close — a television set away.

My old hinterland haunt was once place where, if you wiggled the rabbit-ear antenna just right, you could pull in one or two TV stations. And what could you see? Perhaps reruns of The Brady Bunch, perhaps the news. But about a quarter century ago came VCRs and video stores; then cable and satellite TV; and, finally, the Internet. The serpent had entered Eden.

In the wake of the Sandy Hook tragedy, much fire has been directed at gun advocates in general and the National Rifle Association in particular. In response, the organization has implicated Hollywood and popular culture in general for mainstreaming mindless violence. Yet even many Second Amendment advocates part company with the NRA on this point. After all, blaming entertainment for crime smacks of blaming guns. Yet there's quite a profound difference: guns don't transmit values. But how we use guns— and knives, fists and words — on screen certainly does.

This message is often a tough sell, however, as it's very natural to defend one's entertainment. We grow up with certain shows, movies, characters and music and often become emotionally attached to them; in fact, we may identify with them so closely that an attack upon them can be taken personally. It's the same phenomenon that causes an avid sports fan to defend his favorite team as if it's his favored son. And it is then we may hear that old refrain, "It isn't the entertainment; it's the values learned at home" (they're actually one and the same since entertainment enters the home with, in the least, the parents' tacit approval).

Yet it appears few really believe that refrain. Sure, depending on our ideology, we may disagree on what entertainment is destructive, but that it can be destructive is something on which consensus exists. Just consider, for instance, that when James Cameron's film Avatar was released, there was much talk in the conservative blogosphere about its containing environmentalist, anti-corporate and anti-American propaganda. At the other end of the spectrum, liberals wanted the old show Amos ‘n Andy taken off the air because it contained what they considered harmful stereotypes. Or think of how critics worried that Mel Gibson's Passion of the Christ would stoke anti-Jewish sentiment or that Martin Scorsese's The Last Temptation of Christ would inspire anti-Christian feelings, and how the Catholic League complained that The Da Vinci Code was anti-Catholic. Now, I'm not commenting on these claims' validity. My only point is that when our own sacred cows are being slaughtered, few of us will say, "Well, yeah, the work attacks my cause, but I don't care because it's the values taught at home that really matter."

The truth? Entertainment is powerful. This is why Adolf Hitler had his propaganda filmmaker, Leni Riefenstahl, and why all modern regimes have at times created their own propaganda films. It's why the ancient Greeks saw fit to censor the arts and American localities traditionally had obscenity laws. And it is why, while "The pen is mightier than the sword" and a picture mightier still, being worth a "thousand words," we have to wonder how many words moving footage coupled with sound would be. How mighty art thou, Tinseltown? Well, we worry that a child witnessing one parent continually abuse the other will learn to be violent, as children learn by example. Yet often forgotten is that while a person can model behavior seven feet away from the television, he can also model it seven feet away through the television.

And what effect do our entertainment role models have? Much relevant research exists, and the picture it paints isn't pretty. For instance, a definitive 1990s study published by The Journal of the American Medical Association found that in every society in which TV was introduced, there was an explosion in violent crime and murder within 15 years. As an example, TV had been banned in South Africa for internal security reasons until 1975, at which point the nation had a lower murder rate than other lands with similar demographics. The country's legalization of TV prompted psychiatrist Dr. Brandon Centerwall to predict "that white South African homicide rates would double within 10 to 15 years after the introduction of television…." But he was wrong.

By 1987 they had more than doubled.

Then the Guardiantold us in 2003 that, "…Bhutan, the fabled Himalayan Shangri-la, became the last nation on earth to introduce television. Suddenly a culture, barely changed in centuries, was bombarded by 46 cable channels. And all too soon came Bhutan's first crime wave — murder, fraud, drug offences." The serpent had struck again.

And exactly how it strikes is interesting…and scary. Lt. Col. David Grossman, a former West Point military psychologist and one of the world's foremost experts on what he calls "killology," explains the process well. In his essay "Trained to Kill," he speaks of how the military learned that during WWII only 15 to 20 percent of riflemen would actually shoot at an exposed enemy soldier. Yet this rate was increased to 55 percent during the Korean War and then 90 percent in Vietnam. How? By applying psychological principles, says Grossman, identical to the forces our children are exposed to through entertainment. They are (all quotations are Grossman's):

Brutalization and desensitization: this occurs in boot camp where the training is designed "to break down your existing mores and norms and to accept a new set of values that embrace destruction, violence, and death as a way of life." Entertainment can perhaps be even more effective when doing this to children because the process often starts when they're too young to distinguish between fantasy and reality. Grossman explains:

To have a child of three, four, or five watch a "splatter" movie, learning to relate to a character for the first 90 minutes and then in the last 30 minutes watch helplessly as that new friend is hunted and brutally murdered is the moral and psychological equivalent of introducing your child to a friend, letting [him] play with that friend, and then butchering that friend in front of your child's eyes.

Classical conditioning: the Japanese employed this during WWII. Soldiers would have to watch and cheer as a few of their comrades bayoneted prisoners to death. All the servicemen were then "treated to sake, the best meal they had had in months, and to so-called comfort girls. The result? They learned to associate committing violent acts with pleasure." Likewise, today "[o]ur children watch vivid pictures of human suffering and death, learning to associate it with their favorite soft drink and candy bar, or their girlfriend's perfume."

Operant conditioning: "When people are frightened or angry, they will do what they have been conditioned to do…. [It's] stimulus-response, stimulus-response." Thus, one of the ways the military increased riflemen's willingness to shoot exposed enemies was to switch from the bull's-eye targets of WWII training to "realistic, man-shaped silhouettes that pop into their field of view." The soldiers have only a split-second to engage this new "stimulus" with the response of firing reflexively. As for kids, "every time a child plays an interactive point-and-shoot video game, he is learning the exact same conditioned reflex and motor skills." This can help explain, says Grossman, why robbers under stress will sometimes reflexively shoot victims even when it wasn't "part of the plan."

If the above seems at all simplistic, note that it's a life's work boiled-down to 500 words. Suffice it to say, however, that entertainment has an effect. And do we really consider today's entertainment benign? We've transitioned from a pre-TV America where boys sometimes brought real guns to school for target shooting to a TV-addicted America where boys bring toy guns to school and get suspended. And, of course, the reasons for this societal sea change are complex. But if we're going to point to one factor, is it wiser to blame the AR-15 than PG-13?